Add depends property to Mod annotation for conditional entrypoints

[hedgehog1029]

Fixes #201, alternative to #212

This PR adds the ability to specify entrypoints that will only be loaded if the specified mod ID(s) are present:

@Mod(value = "mymod", depends = {"othermod"})
public class MyEntrypoint {
    public MyEntrypoint(ModContainer mod) {
        // for example, now you can depend on OtherModExtension.class safely
        mod.registerExtensionPoint(OtherModExtension.class, () -> new MyOtherModCompatibility());
    }
}

This is implemented by checking against the LoadingModList - entrypoints with depends missing from the loading list are filtered out early.
We enforce in validate that any dependencies specified in the annotation are also specified in the mods.toml - this ensures the mods are loaded in the correct order. No longer enforced, leave it up to developers to choose.

Please let me know if this is a sane approach! Otherwise I suppose I'll have to rethink and move the filtering to a later step.

Unit tests have been added to validate the new behaviour.

[neoforged-pr-publishing]

• Publish PR to GitHub Packages

[neoforged-compatibility-checks]

@hedgehog1029, this PR introduces breaking changes.
Fortunately, this project is currently accepting breaking changes, but if they are not intentional, please revert them.
Last checked commit: 3a8905b97c3421ccfdc0e195a6c3d6276c20b335.

loader (:loader)

• net/neoforged/fml/common/Mod
  • depends()[Ljava/lang/String;: ❗ Method was made abstract

[vfyjxf]

why not add a new mod depency type to mods.toml to impl this feature?
Adding new members to Mod annotation look weird, fml currently puts all the metadata in toml